That Thing About Taking All The Antibiotics in the Bottle? It's Wrong.

At least when it comes to fighting antibiotic resistance.

Someone—maybe your doctor, maybe your mom—has probably told you that the last pill in the bottle is the one that cures your sickness. You're supposed to finish the whole treatment, even if you feel better, and especially with antibiotics. If you stop too early, the thinking goes, you leave only the strongest bacteria in your body, allowing them to breed so that next time the antibiotics might not work as well. Or you may even leave yourself vulnerable to getting sick again. Thing is, that's wrong. Experts have known this for awhile, according to STAT News.

Instead of finishing the bottle, you should just stop taking the pills when you feel better. That's because the longer bacteria are exposed to antibiotics, the more opportunity they have to develop resistance to them.

"The way I see it is, there is no reason to believe that longer antibiotic courses will protect you from resistance," Otto Cars, an infectious disease specialist at Uppsala University in Sweden, tells Tonic. "In fact, the longer the course, the more resistance is likely to occur." Researchers who study bacterial resistance agree with Cars, but primary care physicians have yet to come around on it. The practice of taking antibiotics for an arbitrary amount of time came about when good intentions were used in place of hard science. "There's very little data on how long to treat most infectious diseases," says Arturo Casadevall, the chair of the department of microbiology and immunology at the Johns Hopkins Bloomberg School of Public Health. "The courses [of antibiotic treatment] are often set by the calendar without any rhyme or reason."

Without specific guidelines for how much antibiotic a patient needs to vanquish a particular kind of bacteria, doctors turn to what they think is best. And being the conservative bunch that they are, they're more likely to prescribe antibiotics even if they aren't totally sure a sickness is bacterial and not viral, and tell them to finish the whole thing just to be on the safe side, Cars says. Patients, in turn, have come to expect—and sometimes demand—antibiotics, even when they aren't necessary. "What is the optimal treatment? If a patient presents with symptoms of pneumonia, do you treat them until their symptoms go away, or that plus one day? That information just doesn't exist," Casadevall says. "It's left open to the judgment of physicians, who are cautious." Plus telling patients to take drugs until they feel better is unspecific; everyone has a different threshold for what "better" means.

In the early days of antibiotics, prescribing arbitrary doses wasn't such a big problem. Doses were low; side effects were few. But today, because of the rising tide of antibiotic resistance, strong doses and combined treatments are needed just to treat run-of-the-mill infections. And that frequently means there's some collateral damage. "When you take antibiotics, we now have pretty good evidence that it's like dropping a bomb on your own indigenous flora, your microbiota," Casadevall says. A demolished microbiome can mean lower defenses to opportunistic bacteria, such as Clostridium difficile, which can cause severe diarrhea. Casadevall says he's seen infections that have set in after a course of antibiotics that have been worse than the condition that put the patient on antibiotics in the first place. So even though antibiotic resistance is usually presented as a community issue, it can have some pretty pronounced effects on individuals, too.

You might be unknowingly doing other things to speed up antibiotic resistance. Lots of patients assume that taking broad-spectrum antibiotics is going to work best to kill whatever bug they've got. But in fact, most would be better off taking as specific and narrow a drug as possible.

Science is still figuring out exactly how bacteria evolve to develop resistance; there's some evidence to indicate bacteria might even be sharing resistance across species. We still don't know what the best dose is for combination antibiotics meant for bacteria that have already developed a fair amount of resistance. What we do know is that someday antibiotics will no longer work, hence why scientists are looking at new, creative approaches to treating disease-causing bacteria, such as nanotechnology and genetic engineering, Cars says.

Ultimately, it's up to the doctors who prescribe antibiotics to move in the right direction. They make suggestions based on their own experience. And well-informed patients can push the conversation—sometimes, even the prescription—in the right direction. If you get a cold, wait a few days before going to the doctor, because the sickness might just resolve itself. Don't ask your doctor for antibiotics, but if your doctor does prescribe them, make sure you're getting the most narrow spectrum possible. And don't be afraid to listen to your body—symptoms tend to be a pretty good indicator of the progress of the infection, and the safest thing to do might to just stop taking them once you feel back to normal.

"In the end…we all have to do our part as patients and physicians," Cars says.